Let's brainstorm..Setting up MinimServer to feed a USB DAC

[classical11]

(10-01-2014 14:15)simoncn Wrote:  

(10-01-2014 10:26)PeteManchester Wrote:  Hi Simon,

I've not experienced that before, not sure what could be causing that problem.

What colour plastic sleeve does the DAC have?

The plastic sleeve is transparent.

I've been doing some experiments and I've found a combination that is sounding very good:

1) The DAC must be plugged into the Pi directly, not into a powered USB hub. When the DAC is plugged into a hub, the audio is broken up and very distorted.

2) The mplayer.conf file must be updated with the setting

ao=alsa:device=hw=0.0

This prevents software resampling of the audio passing through mplayer.

3) MinimServer transcoding should be set to wav24

4) It's best to serve the music from a local instance of MinimServer running on the Pi. When streaming across the network, there are occasional audible minor glitches.

Hi Simon,

Thanks for sharing your observations.

It's interesting that you've had audio glitches when streaming across the network. Were you using Wifi at either end? Do you get glitches when you disable transcoding?

What sort of distortions do you hear when you plug in your DAC into the powered USB hub? Are they very noticeable? Could they be related to the hub you are using?

I haven't had any audio glitches in my setup but there are a few differences to yours. I am using the same DAC (Stoner Acoustics UD110v2) connected to a powered USB hub. However I'm using mpd for playback. Another difference is that I'm not doing any transcoding on the MinimServer end. My files are 16 bit flac and mp3.

I can't hear any noticeable difference if I plug the DAC in the Raspberry Pi or in the USB hub.

The MediaPlayer renderer is running on a Raspberry pi with Raspbian hf. On another Raspberry Pi I have MinimServer and it's reading the library off a USB hard drive (connected to a powered USB hub). Both are connected to the network via wired Ethernet.

A few observations:

- MinimServer has been rock solid for the last month or so. I only restart it occasionally to apply updates.

- I don't hear any glitches even when I stream to 3 devices at the same time (2xRaspberry Pis and a Linux PC, all running MediaPlayer, all through wired Ethernet)

- mpd must be configured in /etc/mpd.conf to use the correct ALSA device for the USB DAC:

Code:

audio_output {
        type            "alsa"
        name            "My ALSA Device"
        device          "hw:1,0"        # Use the right device here
        auto_resample "no"      # disable resampling
}

- Also, set the mixer type to "software" in order to be able to configure the volume, as Pete described in another post:

Code:

mixer_type                      "software"

- I initially had one of the Raspberry Pis running the renderer connected using Wifi but the Wifi drivers were flaky causing it to lose connection every 1-2 days

- MediaPlayer and mpd work very nicely. gapless works flawlessly.

- I am very satisfied with the sound coming out of the DAC when playing standard definition 16 bit flac files (but I don't have a high end system like a Linn for comparison so this is obviously pretty subjective). I would however like to experiment with transcoding to wav24 at some point.

- I am using BubbleUPnP (and sometimes BubbleDS) for the control points.

Cheers,
Ciprian